$900-1000 can get you an extremely good quad core computer with 4gb of RAM, a great video card, 750gb (or more) of storage, DVD RW/R, gigabit lan, and basically anything else you would need. That's more than enough.
For example, a Q6600 would be an ideal processor. Quad 2.4ghz, easily overclockable, $190.
4gb of DDR2 ram from Corsair or Crucial will run you no more than $80.
A Geforce 9800gt (seems like a great gaming card) is like $130, so you could even potentially pick up two.
Huge hard drive is less than $100.
etc.